Namespace-Magic

The namespaces have been around for long time however, it still feel magic. So I start a page to enable magic, in 2019. As time pass it may not be magic anymore or even may become obsolete. An early attempt in Libreswan with Paul.

Design

The namespaces are named as host-testname e.g "east-basic-pluto-01" and "west-basic-pluto-01". Networking is using bridges. Once we scale up we can keep all tests running at the same time there won't be any namespace, bridge, network link name collisons.

Network bridge

The bridges on the host are named uniquely. brswan-<BC>-<csum> . csum is 16bit checksum of testname. The max length of bridge name is 15 characters.

brswan-12-<csum> 
  where csum is checksum of test name. So each test can have unique bridge on the system.
  note 12 is part of our IPv4 addressing. 192.1.2.x network. that connect east, west, and nic.
e.g basic-pluto-01 192.1.2.0/24  brswan12-52501

No bridge for the second eth device on east, west, norht, eg. west eth0, 192.0.1.254/24 has no bridge associated because we don't have sunrise and sunset yet. so eth0 is just hanging in there. this might save us total bridges required on the host.

Network links

Network links are veth type. On the host side they are named as h<host>eX<csum>. e.g east's eth0 is heaste052501, eth1 of east heaste152501. heaste152501 will join the bridge brswan12-52501

FAQ

How detect from inside the namespace

* one way seems to look at eth0. inside namespace "eth1@if107" kvm "eth0:"

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
    link/ether 52:54:00:9e:81:71 brd ff:ff:ff:ff:ff:ff
</rep>

* How find veth's peer inside namespace from a host : link-netns

<pre>
on the host ip link output:

107: hweste164512@if106: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master brswan12-64512 state UP mode DEFAULT group default qlen 1000
    link/ether 4a:34:cd:0e:0c:13 brd ff:ff:ff:ff:ff:ff link-netns west-ikev2-03-basic-rawrsa

from inside the name space

106: eth1@if107: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000
    link/ether 02:10:c8:8e:d2:7e brd ff:ff:ff:ff:ff:ff link-netnsid 0

from the host you get the name space name: "link-netns west-ikev2-03-basic-rawrsa" 
for exaactly which interface from "ip link" you see "106: eth1@if107",  "107: hweste164512@if106"

Scaling issues to navigate

route cache filling up

[2936616.607520] Route cache is full: consider increasing sysctl net.ipv[4|6].route.max_size.
[2936616.607908] Route cache is full: consider increasing sysctl net.ipv[4|6].route.max_size.
[2936616.609100] Route cache is full: consider increasing sysctl net.ipv[4|6].route.max_size.

sysctl -a | grep "route.max_size"

net.ipv4.route.max_size = 2147483647

google suggest flushing the route cache. That does not seems to help. I think routes are stuck inside namespaces.

ip route flush cache

ip route show cache is empty

ip -all netns exec ip link show
show weired errors.

ip -all netns exec ip link show

netns: east-ikev2-mobike-06
setting the network namespace "east-ikev2-mobike-06" failed: Invalid argument

iptable fails -w 60 seems to help

sudo /usr/bin/nsenter --mount=/run/mountns/west-nstest-4 --net=/run/netns/west-nstest-4 --uts=/run/utsns/west-nstest-4 /bin/bash -c 'cd /testing/pluto/nstest-4;iptables -I INPUT -m policy --dir in --pol ipsec -j ACCEPT
'
Another app is currently holding the xtables lock. Perhaps you want to use the -w option?

I tried putting less /root/.bashrc

alias iptables="iptables --wait 60 --wait-interval=100000"

That seems to have reduced the failure rate from 50% to 2%, when running 500 tests 10 tests in parallel. Changing to --wait 120 still cause 1.3% errror. Going above 120 seconds would skew tests. They usually timeout in 120 seconds

would this work on foo 7/CentOS7: not yet too old util-linux

unshare and or nsenter do not suppor --mount[=file] option.

seems to be some options.

fedora 28 
unshare -V
unshare from util-linux 2.32.1

-m, --mount[=file]
   Unshare the mount namespace.  If file is specified, then a persistent namespace is cre‐ated
   by a bind mount

---- old one foo 7 -----
unshare -V
unshare from util-linux 2.23.2

-m, --mount
   Unshare the mount namespace.

outstanding issues

reduce the use of iptables =

This would go in steps. First make sure the swan-prep crate the LOGDROP traget only when a test need it. grep in the test scripts for LOGDROP. So mostly it will only run on the initiator.

"Error: Peer netns reference is invalid." =

It seems when the namespaces get mangled up any "ip" command would output this error. For now I am sanitizing it.

python threads locking up

It seems often the the workers, started using ProcessPoolExecutor seems to lock up. They sit there doing nothinng I have been looking at them using gdb

gdb  /usr/bin/python3.7 -p <pid>
(gdb) py-bt
Traceback (most recent call first):
  File "/usr/lib64/python3.7/multiprocessing/synchronize.py", line 95, in __enter__
    return self._semlock.__enter__()
  File "/usr/lib64/python3.7/multiprocessing/queues.py", line 93, in get
    with self._rlock:
  File "/usr/lib64/python3.7/concurrent/futures/process.py", line 226, in _process_worker
    call_item = call_queue.get(block=True)
  File "/usr/lib64/python3.7/multiprocessing/process.py", line 99, in run
    self._target(*self._args, **self._kwargs)
  File "/usr/lib64/python3.7/multiprocessing/process.py", line 297, in _bootstrap
    self.run()
  File "/usr/lib64/python3.7/multiprocessing/popen_fork.py", line 74, in _launch
    code = process_obj._bootstrap()
  File "/usr/lib64/python3.7/multiprocessing/popen_fork.py", line 20, in __init__
    self._launch(process_obj)
  File "/usr/lib64/python3.7/multiprocessing/context.py", line 277, in _Popen
    return Popen(process_obj)
  File "/usr/lib64/python3.7/multiprocessing/process.py", line 112, in start
    self._popen = self._Popen(self)
  File "/usr/lib64/python3.7/concurrent/futures/process.py", line 593, in _adjust_process_count
    p.start()
  File "/usr/lib64/python3.7/concurrent/futures/process.py", line 569, in _start_queue_management_thread
    self._adjust_process_count()
  File "/usr/lib64/python3.7/concurrent/futures/process.py", line 615, in submit
    self._start_queue_management_thread()
  File "/home/build/libreswan/testing/utils/nsrun", line 3790, in run_ns_q_conc
    except KeyboardInterrupt:
  File "/home/build/libreswan/testing/utils/nsrun", line 3744, in do_test_list_new
    else:
  File "/home/build/libreswan/testing/utils/nsrun", line 3985, in main
    return
  File "/home/build/libreswan/testing/utils/nsrun", line 4069, in <module>

gdb magic to get python bt
dnf debuginfo-install python3
dnf debuginfo-install python3-3.7.3-3.fc29.x86_64

good to know

nsenter alias/function

NSENTER()
{
 ns=$1
 nsargs="--mount=/run/mountns/${ns} --net=/run/netns/${ns} --uts=/run/utsns/${ns}"
 NSENTER_CMD="/usr/bin/nsenter ${nsargs} "
 sudo ${NSENTER_CMD} /bin/bash
}

# Then type

NSENTER east-basic-pluto-01